Olefin reactions with boron fluoride catalyst



Patented Aug. 26, 1941 OLEFIN naac'rrons wrrn nonoN rwomna os'rnmzsrDonald John Lode'r, Wilmington, net, assignor to E. I. du Pont deNcmours & Company,Wilmington, Del., a corporation of Delaware NoDrawing.

8 Claims.

This invention relates to'a new catalyst for organic synthesis and moreparticularly to boron halide catalysts and is in part 'a'continuation ofmy application Serial No. 46,875, filed October 26, 1935, U. S. PatentNo. 2,158,031.

In the Friedel-Crafts reactions for the synthesis of aromatichydrocarbons, ketones and triphenyl methane derivatives, anhydrousaluminum chloride or an analogous anhydrous halide such as boronfluoride, have been used as the condensing agents. These agents are,used in comparatively large proportions as they form, in suchreactions, well-defined addition compounds which are in many reactionsconsidered to be the reactive agents. Due to the nature of thematerials, the reaction is conducted under anhydrous conditions andrecovery of the final products usually involves treatment of thereaction mixture with ice or ice and water. The aluminum halide andanalogous halides are thus hydrated and the involved expensive stepsrequired to reconvert them to the anhydrous form generally renderssyntheses of this nature commercially unattractive. I

An object of the present invention is to provide a new class ofcondensing or catalytic agents prepared from boron-halogen containingcom pounds. A further object of the invention is to provide a new andimproved class of condensing agents particularly for reactions requiringan acid type condensing agent, such, for example, as: the interaction ofalcohols with carbon monoxide to obtain acids and esters, theinteraction of olefins and carbon monoxide to produce acids and esters,the interaction of organic acids With olefins to provide high molecularweight esters, and many of the reactions of the Friedel-Crafts type. Astill further object of the invention is to provide hydrated boronhalide catalysts for accelerating organic reactions of the above'types.Other objects and advantages of the invention will hereinafter appear.

I have found that organic reactions such as the preparation of organicacids and their esters by the interaction of carbon monoxide withalcohols, ethers, esters, olefins and reactants which decompose to formsuch compounds, as well as the Friedel-Crafts type of reactions in whichwater is not detrimental, can be catalyzed with certain hydrated borontrihalides. These catalysts are particularly efie'ctive in reactionsrequiring superatmospheric pressures. They are also well fitted forcatalyzing generally such organic condensation reactions in which wateris not detrimental and which require an acidic type Application June 24,1938, Serial No. 215,580

(or. m an) catalyst; they are especially adapted for reactions inwhichccarbon monoxide is one of the Reaction 4 by substituting the aryl,CsHs, for R,

benzene would react with CO to form benzaldehyde. Moreover, alcohols andmore specifically the lower aliphatic monohydric alcohols may likewisebe reacted with olefins in accord with this invention to give ethers.

My preferred condensing agents for reactions such as those illustratedabove and their equivalents are the boron trihalides associated withwater in the ratio ranging preferably from one to live mols per mol ofboron trihalide. More spe'fciflcally they include the boron trihalidesassor ciated with water as a mono-; di-, tri-, and quatrihydrate of thetrichloride, trlfiuoride, tribromide, or trilodide of boron.Furthermore, as the boron trihalides form intermediate products whichmay be designated as intermediate hydrates between those definitelystated above, it is understood that such hydrates are likewise suitableas condensing agents.

It has been stated heretofore that the principal difliculty encounteredin the use of anhydrous halides, and more particularly aluminum halide,

arose from the necessary destruction of the condensing agent prior tothe recovery of the products of the reaction. An additional difllcultyin the use of such agents is encountered in handling the anhydrousagents and maintaining them in the anhydrous form. The condensing agentsof the present invention can be readily separated by distillation,extraction, decantation or by other means from the reaction products andthe recovered agents, generally without the necessity of purification,can be reused directly to accelerate another reaction. The strikingadvantages of these recoverable highly reactive condensing agents overthe anhydrous condensing agents are self-evident.

Generally the condensing agents may be prepared by reacting a liquidhalogen acid with a boric acid. For example, three mols of liquidhydrofluoric acid may be reacted with one mol of solid orthoboric acidto give the liquid trihydrate of boron trifluoride or three mols ofliquid hydrofluoric acid may be reacted with one-halt a mol of metaboricacid to give the dihydrate of boron trifluoride.

- I shall now describe more specifically methods of preparing thecondensing agent of the invention and also processes in which they maybe used but it will be understood that the details therein given willnot limit the scope oi the invention.

Example 1,-1696 parts by weight of solid orthoboric acid are placed in asuitable pressure sustaining receptacle and 1643 parts by weight ofliquid hydrofluoric acid are added thereto. The temperature of theexothermic reaction is kept at approximately 0., and when the reactionof thehydrofluoric acid with the boric acid is complete a liquid, fairlymobile trihydrate of boron trlfluoride, having a specific quantity of1.500 to 0., is obtained.

Example 2.468 parts by weight of liquid hydrofluoric acid are combinedas in Example 1 with 175 parts by weight of metaboric acid. The liquidcatalyst obtained is apparently a dihydrate of boron trlfluoride havinga specific gravity of 1.625 at 20 C.

As has already been emphasized the condensing agents of the presentinvention may be utilized in a number of reactions and are mostadvantageously employed in condensation reactions in which water is notdetrimental. I shall now give several examples illustrating types ofprocesses in which my preferred condensing agents are employed, but theutility of the catalysts is not limited by or to these processes.

Example 3.-205 parts by weight of the trihydrate of boron trifluorideobtained as described in Example 1 are placed in a pressure resistingautoclave and 54 parts by weight of methanol added. The autoclave isclosed and carbon monoxide is added to the mixture contained thereinuntil a pressure of approximately 900 atmospheres is attained. Thetemperature is held at approximately 260 0., and the reaction iscontinued until analysis shows that an equivalent weight of carbonmonoxide has reacted with the methanol present. The pressure is releasedand the acetic acid distilled from the reaction mixture, steam beingadded during the distillation to maintain a fairly constant water toboron trifluoride ratio. A 79% yield of acetic acid was obtained whenthis reaction was conducted under the above conditions.

Example 4 .A mixture of 64 parts by weight 01' methanol and 175 parts byweight of the catalyst prepared in accord with the directions given inExample 2 was charged into a pressure shaker tube. The mixture washeated to 240-250 0., under a 00 pressure of approximately 900atmospheres for about 1 hours during which a pressure drop ofapproximately 570 atmospheres occurred. The tube was cooled, thepressure discharged, and the product again heated to 160 0., undercylinder ethylene pressure for approximately of an hour during thecourse of which treatment a considerable pressure drop occurred. Aftercooling, the product was discharged and distilled directly giving avolume of crude ethyl acetate of 58.8 parts by weight having a boilingrange of 61-72 C. The distillation was continued and acetic acid and anacetic acidboron fluoride addition compound condensed in the distillate.

Example 5.-Ethanol was reacted according to the conditions and proceduregiven in Example 1 with a yield of 45-50% of the amount of propionicacid which is theoretically obtainable according to the equation:

Example 6.Formalin, 172 parts by weight, was caused to absorb 150 partsof boron fluoride gas. The resulting mixture absorbed propylene at from0 C.-20 0., and one atmosphere pressure, forming a product which, whenmade alkaline, and distilled, yielded a series of formals. The lowerboiling products (distilling at 30 to 123 0.,) were separated by saltingout; the material distilling over below 0., was purified byredistillation and the boiling point of the chief constituent, butyleneglycol cyclic formal, was 113-114.3 C. The higher boiling formals wereobtained by continuing the distillation and collecting fractions between123 and 250 C. Still higher boiling compounds remained in the residue.The yield of the low boiling products, obtained in the salting outprocess was 56 parts by weight and the yield of products boiling 123 C.to 250 0., was 15 parts by weight.

Example 7. 100 parts of a complex containing 2 mols oi acetic acid permol of BF; and 20 parts of benzoyl peroxide were charged into a glasspressure shaker tube. Propylene, which was introduced to give a pressureof 25 to 30 pounds per square inch, was rapidly absorbed. The heat ofthe reaction increased the temperature to 30 to 35 C. Propyl acetate wasrecovered from the reaction product in good yield.

Example 8.-125 pants of (CHsCOOI-I) zBFa was charged into a pressuretube and ethylene added to build up a pressure of 800 pounds per squareinch. Over a period of 3 hours the temperature increased from 94 0. to153 0. 147 parts of product was recovered which upon analysis gave a 40%conversion of the acetic acid to ethyl acetate.

My condensing agents may be used in various proportions which aregoverned by the type of reaction. In the absence of addition agents suchas metal oxides or powdered metals, for example, nickel and nickeloxides, they may be used in proportions ranging from 0.25 to 2.0 mol orhigher calculated on the boron halide present per mol of the majorreactant while in the presence of addition agents much lower amounts maybe employed, say, generally; from 1 to 5% and, in some instances, higherpercentages may be required. The activity of the addition agentdetermines in large measure the amount required, the particu- I are wellillustrated by lar reaction as well as the temperature and pressureconditions employed also being considered.

As indicated in the examples the reactions herein involve the additionof one compound to another to form a third compound. Accordingly it willbe understood that when the words condense, condensing, and"condensation are used herein, they designate such reactions which theequations given above.

From a consideration of the above specification it will be realized thatmany changes may be made in the catalysts herein described and themethod of their preparation without departing from the invention orsacrificing any of the advantages that may be derived therefrom.

I claim:

1. In a liquid phase process involving an organic condensation reactionof an olefin with a member of the group consisting of lower aliphaticmonohydric alcohols and lower fatty acids, respectively, the stepsgwhichcomprise effecting the reaction in the presence of boron trifluorideassociated with from one to five mols of water per mol of borontrifluoride and recovering from the products of the reaction borontrifluoride associated with water.

2. In a liquid phase process involving an organic condensation reactionof an olefin with a member of the group consisting of lower aliphaticmonohydric alcohols and lower fatty acids, respectively, the steps whichcomprise effecting the reaction in the presence of a dihydrate of borontrifluoride and recovering from the products of the reaction borontrifluoride associated with water.

3. In a liquid phase process involving an organic condensation reactionof an olefin with a member of the group consisting of lower aliphaticmonohydric alcohols and lower fatty acids, respectively, the stepswhichcomprise eflfecting the reaction in the presence of a trihydrate ofboron trifluoride and recovering from the products of the reaction borontrifluoride associated with water.

4. A liquid phase process which comprises effecting the reaction betweena lower fatty acid and an olefin in the presence of boron trifluorideassociated with from one to five mols of water per mol of borontrifluoride and recovering from the products of the reaction borontrifluoride associated with water.

5. A liquid phase proces effecting the reaction between a lower fattyacid and an olefin in the presence of a dihydrate of boron trifluorideand recovering from the products of the reaction boron trifluorideassociated with water. a

6. A liquid phase process which comprises effecting the reaction betweena lower fatty acid and an olefin in the presence of a trihydrate ofboron trifluoride and recoveringfrom the products of the reaction borontrifluoride associated with water.

7. A process of preparing ethyl acetate which comprises effecting thereaction between acetic acid and ethylene in the presence of a borontrifluoride dihydrate catalyst.

8. A process of preparing propyl acetate which comprises effecting thereaction between acetic acid and propylene in the presence of a borontrifluoride dihydrate catalyst.

DONALD JOHN LODER.

which comprises I

